METHOD FOR DEPOSITING A CELLULOSIC FIBER COMPOSITION ON A SUBSTRATE

Abstract

A method for depositing, on a substrate, a composition of cellulosic fibers, includes preparing an aqueous suspension SA comprising at least cellulosic fibers, spraying, at a pressure no lower than 3 MPa, the aqueous suspension SA onto a substrate, wherein the spraying is carried out by means of a nozzle having a size between 0.05 mm and 3 mm, and obtaining a fibrous deposit DF on the substrate. The aqueous suspension SA includes at least 3% by weight of cellulosic fibers relative to the total weight of the aqueous suspension SA, and the aqueous suspension SA and the fibrous deposit DF have dry matter with identical composition.

Claims

1. A method for depositing, on a substrate, a composition of cellulosic fibers, comprising the following steps: 1/ preparing an aqueous suspension SA comprising at least cellulosic fibers, 2/ spraying, at a pressure no lower than 3 MPa, the aqueous suspension SA onto a substrate, wherein the spraying is carried out by means of a nozzle having a size between 0.05 millimeter and 3 millimeters, 3/ obtaining a fibrous deposit DF on the substrate, the aqueous suspension SA comprising at least 3% by weight of cellulosic fibers relative to the total weight of the aqueous suspension SA, the aqueous suspension SA and the fibrous deposit DF having dry matter with identical composition.

2. The method according to claim 1, wherein the aqueous suspension SA comprises between 3 and 20% by weight of cellulosic fibers, relative to the total weight of the aqueous suspension SA.

3. The method according to claim 1, wherein the cellulosic fibers have an average length between 50 micrometers and 5 millimeters.

4. The method according to claim 1, wherein, for 100 parts by weight of dry matter of the aqueous suspension SA, the cellulosic fibers account for 3 to 100 parts by weight.

5. The method according to claim 1, wherein the aqueous suspension SA also comprises mineral fillers.

6. The method according to claim 1, wherein the aqueous suspension SA comprises mineral fillers, these mineral fillers accounting for 0 to 97 parts by weight for 100 parts by weight of dry matter of the aqueous suspension SA.

7. The method according to claim 1, wherein the substrate is paper or cardboard.

8. The method according to claim 1, wherein the spraying of step 2/ is carried out at a pressure between 3 MPa and 50 MPa.

9. The method according to claim 1 wherein the spraying of step 2/ is carried out by means of a nozzle having a size between 0.1 millimeter and 2.0 millimeters.

10. The method according to claim 1, wherein the fibrous deposit DF has homogeneous grammage over at least 90% of its surface, homogeneous grammage being grammage that varies by less than 5% over the entire surface of the fibrous deposit DF.

11. The method according to claim 1, wherein the fibrous deposit DF has a grammage between 0.2 g/m.sup.2 and 50 g/m.sup.2.

12. The method according to claim 1, wherein the spraying of aqueous suspension SA results in microdroplets having a size between 1 and 800 micrometers.

13. The method according to claim 1, wherein the DF deposit has a thickness that ranges from 0.2 to 50 micrometers.

14. The method according to claim 1, wherein step 2/ is carried out 1 to 20 times on the substrate.

15. A method for forming, on a substrate, a barrier layer comprising the following steps: 1′/ preparing an aqueous suspension SA comprising at least 3% by weight of cellulosic fibers relative to the total weight of the aqueous suspension SA, 2′/ depositing by spraying, at a pressure no lower than 3 MPa, the aqueous suspension SA onto a substrate, wherein the spraying is carried out by means of a nozzle having a size between 0.05 millimeter and 3 millimeters, 3′/ obtaining a barrier layer made up of a fibrous deposit DF on the substrate, the aqueous suspension SA and the fibrous deposit DF having dry matter with identical composition.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0095] FIG. 1 shows the spraying, at a pressure no lower than 3 MPa, of a cellulosic fiber composition according to the method that is the subject matter of the invention.

[0096] FIG. 2 shows the spray coating of a cellulosic fiber composition.

DETAILED DESCRIPTION

[0097] A composition of cellulosic fibers was deposited on a substrate (80 g/m.sup.2 printing and writing paper) according to the following steps:

[0098] a) preparation of an aqueous suspension SA comprising, by weight:

[0099] 95% at least of water,

[0100] 1 to 2% of calcium carbonate,

[0101] 3 to 4% of cellulosic fibers from MOW (Mixed Office Waste containing 85 wt % fibers and 15 wt % fillers in water),

[0102] b) spraying of the aqueous suspension SA onto 80 g/m.sup.2 printing and writing paper, the spray pressure being 95 bar with a flow rate of 2.3 L/min,

[0103] c) drying in open air at 30° C. for 25 minutes,

[0104] d) obtaining a fibrous deposit DF of 1.5 g/m.sup.2 on 80 g/m.sup.2 printing and writing paper.

[0105] The spraying nozzle has a size of 600 micrometers. The cellulosic fibers have an average length of 400 micrometers.

[0106] This deposit is shown by FIG. 1. The spraying conditions produce microdroplets while the conditions of the prior art (spray coating, FIG. 2) produce large, irregularly sized drops.

[0107] The same procedure was followed in order to prepare the deposits of Tables 1 and 2.

TABLE-US-00001 TABLE 1 Cellulosic fiber films Fibers/ wt % fillers Deposit Thickness Sample Technology Fibers Fillers in water Fillers (g/m.sup.2) (μm) 1 Invention BEKP 100/0 0 28 17 2 Invention BEKP 100/0 0 50.6 22 3 Invention BEKP 100/0 0 88.3 93 4 Invention BEKP 100/0 0 57.4 27 5 Invention BEKP 100/0 0 58 22 6 Invention BEKP 100/0 0 62.1 24 7 Invention BEKP 100/0 0 90.8 32 8 Invention BEKP 100/0 0 56.6 27 9 Coating BEKP 100/0 0 1 6 10 Coating OCC  90/10 11 Pigment 1.5 6 11 Coating BEKP  20/80 80 Calcium 15 36 carbonate 12 Coating BEKP  20/80 80 Calcium 10 18 carbonate 13 Coating BEKP  20/80 80 Calcium 5 12 carbonate BEKP Bleached Hardwood Kraft Pulp: cellulose fibers having a mean size of 200 micrometers OCC Old Corrugated Cardboard: cellulose fibers having a mean size of 200 micrometers Fillers Pigment and Calcium carbonate having a mean size of 10 micrometers

TABLE-US-00002 TABLE 2 Spraying conditions Distance between the Pressure nozzle and the substrate Number Drying Sample Nozzle (bar) (cm)/nozzle size (μm) of spray(s) (° C.) Substrate 1 25.13 60 50/550 15 100 Nylon 2 25.13 120 50/550 15 100 Nylon 3 30.13 60 50/610 15 100 Nylon 4 30.13 120 50/610 15 100 Nylon 5 25.13 60 50/550 15 25 Glass 6 25.13 120 50/550 15 Ambient25 Glass 7 30.13 60 50/610 15 Ambient25 Glass 8 30.13 120 50/610 15 Ambient25 Glass 9 25.13 40 55/550 1 105 Paper 10 25.13 40 50/550 1 25 OCC 11 25.13 40 50/550 15 50 OCC 12 25.13 40 50/550 10 50 OCC 13 25.13 40 50/550 5 50 OCC 1 bar = 0.1 MPa

[0108] The nozzle type are 25 or 30 and is defining the nozzle type and average diameters.

TABLE-US-00003 TABLE 3 Nozzle features Nozzle Type Equivalent diameter in μm Spray angle in ° 25.11 550 60° 25.13 550 67° 30.11 610 60° 30.13 610 67°